The present invention relates generally to recording devices and more particularly to a recording arrangement wherein a recording means may be mounted in a very simple manner within an overall arrangement which is designed to emphasize simplicity. More specifically, the invention relates to the type of apparatus wherein a stylus mounted at the end of a recording lever cooperates with a recording medium and is moved transversely to the direction of movement of the recording medium while also exhibiting the capacity for being lifted from the recording means.
In recording devices such as that to which the present invention relates, it is important that the apparatus be capable of allowing exchange or replacement of the recording medium without damage thereto. For example, when the recording medium is to be exchanged, it must be capable of accomplishment without scratching the recording medium and without damage to the stylus. The capacity for avoiding damage to the recording medium and to the recording apparatus is especially important in devices where it is not possible to move the recording medium away from the recording device as is the case, for example, in tachographs where the recording medium is mounted in a tiltable lid. In such arrangements, it is especially important that a recording apparatus exhibiting good design features be provided in order not only to provide desirable operating characteristics but also to avoid expensive construction.
If it is desired to provide a mounting for a recording apparatus involving a relatively simple design, it will be found that two principal solutions will arise. In one such solution, a mounting axis is arranged in a plane parallel to the plane of the recording medium. In the other solution, the axis is arranged in a plane normal or perpendicular to the plane of the recording medium.
Within the aforementioned limits, a design in accordance with the prior art wherein a slide exclusively guided in one dimension, that is, in a direction transverse to the transport direction of the recording medium, is of such a nature that it cannot be given extensive consideration. Such a slide is of the type tiltably mounting a recording means which is lowered to or lifted from the recording medium, by electromagnetic means.
In the first solution mentioned, the recording movement is achieved by axially moving the recording means which is mounted by means of a suitable bearing mechanism on an axle while the recording point or stylus is lifted from the record medium by rotation of the recording means around the axis.
Such a mounting arrangement for a recording device is advantageous insofar as relatively large recording movements are possible with a linear movement of the recording point and as several recording means may be mounted on the same axle when they are staggered in a suitable manner.
However, such a staggered arrangement is often difficult to achieve from a practical viewpoint since the ranges of recording will overlap each other or be very close to each other. Also, for reasons of design, and in order to achieve better utilization of available space, different mounting arrangements are preferable, especially in cases where several recording devices for small recording movements must be arranged adjacent each other. It is of decisive disadvantage, however, where the mounting part for the recording means must be axially moved during recording since bearing means must be of a very high quality. In order to avoid slanting of the bearing means due to forces influencing the recording means, it becomes also necessary to arrange the bearing means not only at a relatively far distance from each other but also to make them free of tolerance variations. This gives rise to high cost in production and also to high frictional loads which must be taken into consideration with regard to the drive means for the recording device.
In comparison with devices of the type described above, there would arise fewer driving problems in an arrangement where the recording means is capable of being rotated or tilted around its axle in order to lift the recording point off the recording medium, inasmuch as this action is normally effected by manual operation, for instance by opening the lid of the apparatus or when a lock or the like is actuated. Simultaneously, of course, with respect to the tilting movement of the recording means, there will arise more favorable conditions with regard to the friction which is developed than with respect to the recording drive so that such an arrangement of the mounting means would be a serious error with respect to prevailing driving conditions.
With respect to such an adaptation, other possible arrangements of the mounting means for the recording means by functionally reversing the parts is considered to be advantageous when arc-shaped recording lines may be accepted or when the recording movement is relatively small. This is all the more applicable with regard to desired relative simplicity in design and mounting arrangement for recording means where a straightline motion mechanism or the like is not an acceptable choice because of its high expense.
A problem which arises from such a mounting arrangement of a recording device relates to the manner which must be utilized for lifting the recording point or stylus off the record medium. In known recording arrangements, this has been solved in that the axle for mounting the recording means is mounted on a carrier rotatably connected to the recording device. In another solution, the recording means is mounted to be axially displaceable on the axle.
With regard to the aforementioned first solution, consideration must be given to the fact that it is only of limited use with a view to the recording tolerances to be expected. In many cases it may also not be realized for reasons of design. The second solution is functionally, and from a design viewpoint, relatively simple. However, it requires a relatively large amount of space since the recording lever and, therefore, the entire recording means must be lifted off the record carrier parallel thereto when there is sufficient distance between the recording point and the record carrier. Also, in this case, it is difficult to avoid slanting so that by a corresponding design it must be avoided that a tilting movement is produced transversely to the axis when the recording means is lifted off.
In this connection it is also known to lift the recording means off the recording medium only a short distance and thereafter to rotate its axis so that it is no longer over the recording medium. The main disadvantage of this solution relates to its space requirements so that the use of several recording means is limited or rendered impossible within the individual recording apparatus.
Of course, the recording device according to the previously mentioned slide arrangement may be mounted on a carrier which is in itself rotatably mounted on an axis normal to the recording plane and which is in a suitable driving connection with the recording driving means. This solution is mentioned in this connection only to provide a complete consideration of the available alternatives but not to indicate that it is considered a solution which would allow achievement of the desired objective. Here, the recording means is mounted on an axle which is fastened to carrier means and is arranged in a plane parallel to the record carrier on which axle the recording means is rotatably mounted so that its recording point can be lifted off the record carrier against the force of the spring.
Accordingly, it is the aim of the present invention to provide a recording mechanism which will generally avoid and overcome many of the problems which arise in prior devices.